Video apparatus using several video signal sources and process for controlling such a video apparatus

ABSTRACT

A video apparatus has a first connector for outputting first RGB signals, a second connector for receiving second RGB signals, and an On-Screen Display circuit generating third RGB signals. A RGB generator generates fourth RGB signals. A first RGB switch is connected to the second connector and to the On-Screen Display circuit for receiving respectively said second RGB signals and said third RGB signals. The first RGB switch outputs fifth RGB signals. A second RGB switch is connected to the first RGB switch and to the RGB generator for receiving respectively said fifth RGB signals and said fourth RGB signals. The second RGB switch outputs the first RGB signals. A process to control such a video apparatus is also proposed.

This application claims the benefit, under 35 U.S.C. § 365 ofInternational Application PCT/EP01/09854, filed Aug. 27, 2001, which waspublished in accordance with PCT Article 21(2) on Mar. 14, 2002 inEnglish and which claims the benefit of European patent application No.00402485.7 filed Sep. 8, 2000.

The invention relates to a video apparatus using several video signalsources and to a process for controlling such a video apparatus.

A video apparatus generally has a connector to output video signals toanother video apparatus, for instance a display. Such a connector cancarry a video signal represented by three monochrome signals, namely ared signal R, a green signal G and a blue signal B. For instance, onconventional Scart connectors, pins 15, 11 and 7 are used for thispurpose.

So far, the RGB signals coming out on this connector where generated byan On-Screen Display circuit under control of a micro-processor. It hasalso been proposed to transmit on this connector RGB signals received onanother connector of the video apparatus, for instance an input Scartconnector, generally called Scart2. The signal received on Scart2 werefor instance signals from a set-top box.

The invention seeks to take advantage of another source of video signalin RGB format and still to be able to transmit it through a conventionalconnector.

The invention proposes a video apparatus with a first connector foroutputting first RGB signals, with a second connector for receivingsecond RGB signals, and with an On-Screen Display circuit generatingthird RGB signals, wherein a RGB generator generates fourth RGB signals,wherein a first RGB switch is connected to the second connector and tothe On-Screen Display circuit for receiving respectively said second RGBsignals and said third RGB signals, wherein the first RGB switch outputsfifth RGB signals, wherein a second RGB switch is connected to the firstRGB switch and to the RGB generator for receiving respectively saidfifth RGB signals and said fourth RGB signals, and wherein the secondRGB switch outputs the first RGB signals.

Some of the preferred features of the invention are the following:

-   -   the first RGB switch is controlled by a first fast-blanking        signal generated by the On-Screen Display circuit;    -   a first OR-gate generates a second fast-blanking signal based on        said first fast-blanking signal and on a fast-blanking signal of        the second connector;    -   said second fast-blanking signal controls the second RGB switch;    -   a second OR-gate generates a third fast-blanking signal based on        said second fast-blanking signal and on a fast-blanking signal        of the RGB generator;    -   said third fast-blanking signal is output on a pin of the first        connector;    -   said third fast-blanking signal is output on a pin of the first        connector through an amplifier;    -   a source switch allows to connect a composite video signal pin        of the second connector to a digital generator, a digital switch        allows to connect the digital generator to a digital decoder        generating said fourth RGB signals and a muting circuit is        inserted between the second connector and the first RGB switch.

The invention also proposes a process for controlling such a videoapparatus comprising the steps of:

-   -   controlling the source switch to connect the composite video        signal pin of the second connector to the digital generator;    -   controlling the digital switch to connect the digital generator        to the digital decoder;    -   controlling the muting circuit to mute said second RGB signals.

According to a preferred feature, it includes the subsequent step ofcontrolling the On-Screen Display circuit to output RGB signalsindicating said second RGB signals are muted.

The invention and other features thereof will be understood in the lightof the following description made with reference to the attacheddrawings where:

FIG. 1 represents a first embodiment of a video apparatus according tothe invention;

FIG. 2 represents a second embodiment of a video apparatus according tothe invention;

FIG. 3 represents a preferred embodiment of the video generator of FIG.2.

In the following description, reference numbers 1 to 20 are dedicated tothe corresponding pins of the Scart connector according to the norm. Itshould also be noted that the ground wires are not represented forbetter clarity of the drawings.

The main elements of the video processing circuits of a video recorderare represented on FIG. 1. The video recorder comprises a CVBS generator22, a S-Video generator 24 and a RGB generator 46.

Such a VCR can read video tapes recorded according to the VHS standardand thus generate a CVBS signal on the output of the CVBS generator 22in a conventional way. The CVBS generator 22 represents the set of partswhich are used to generate the CVBS signal from the signal recorded onthe tape.

In a similar way, the VCR can read video tapes recorded according to theS-VHS standard thanks to the S-Video generator 24 which outputs separateluminance Y and chrominance C signals.

Lastly, the VCR can read video tapes recorded according to the D-VHSstandard and outputs notably corresponding RGB signals on outputs R₄₆,G₄₆ and B₄₆ in accordance with a fast blanking signal FB₄₆. In thedescribed embodiment, the RGB generator 46 is a MPEG decoder STI5500from ST fed by a bit-stream processor SAA6700H from Philips according todata read on a tape in a digital format. Of course, another medium couldbe used: for instance, the video signal represented by R₄₆, G₄₆, B₄₆could be taken from a video disc or a hard disc.

The VCR also includes an On-Screen Display (OSD) circuit 26 for thepurpose of displaying menus on a display (for instance a TV set) towhich the VCR can be linked via a Scart connector 28.

The OSD circuit 26 generates three separate monochrome signals(respectively red signal R_(OSD), green signal G_(OSD) and blue signalB_(OSD)) according to the RGB format and a fast blanking signal FB_(OSD)indicating to the display when these RGB signals should be taken intoaccount (high level of FB_(OSD)).

The OSD circuit 26 receives instructions from a micro-processor 30 via adata bus I represented as a single wire on FIG. 1 for simplification.

The VCR includes a further Scart connector 38, called Scart2, which pinswill be referenced as 1′ to 20′. This Scart2 connector 38 allows toconnect an external video device to the VCR, for instance a digitalset-top box which is able to receive video information from satellitesor a cable link. Video sequences are allowed to enter the VCR on pins7′, 11′ and 15′ of Scart2 connector 38 in a RGB format as a picture tobe superimposed on the sequences carried on composite signal pin 19′ orgenerated by the VCR, according to an OSD technique.

The RGB signal received on the pins of the Scart2 connector 38 (composedas usual of three separate monochrome signals R₂, G₂ and B₂) isforwarded to a first RGB switch 40 on three respective inputs. Threeother inputs of the first RGB switch 40 receive respectively the threemonochrome signals R_(OSD), G_(OSD) and B_(OSD) from the OSD circuit 26.

The Scart2 connector 38 also outputs a fast blanking signal FB₂ on itspin 16′ in accordance with the RGB signal from pins 7′, 11′ and 15′.

The first RGB switch 40 also receives the fast blanking signal FB_(OSD)from the OSD circuit 26. When FB_(OSD) is high, the first RGB switch 40transmits on its three RGB outputs R₄₀, G₄₀, B₄₀ respectively theR_(OSD), G_(OSD) and B_(OSD) signals; at the opposite, when FB_(OSD) islow, the first RGB switch 40 transmits on its three RGB outputs R₄₀,G₄₀, B₄₀ respectively the R₂, G₂ and B₂ signals. The RGB signal outputfrom the first RGB switch 40 is thus the image from Scart2 connector 38with superimposed parts of image generated by the OSD circuit 26.

It can be noted that a muting circuit 45 is interposed between theScart2 connector 38 and the first RGB switch 40. The muting circuit 45is controlled by the micro-processor 30 in order to mute the RGB signalsfrom the Scart2 connector 38 when they are not synchronised with thesignal output on pin 19 of the Scart connector 28.

A first OR-gate 44 combines the fast blanking signal FB₂ from the Scart2connector 38 and the fast blanking signal FB_(OSD) from the OSD circuit26. The output FB₄₄ of the OR-gate 44 is thus at a high level wheneither the fast blanking signal FB₂ from the Scart2 connector 38 is orthe fast blanking signal FB_(OSD) from the OSD circuit 26 is at a highlevel. At the opposite, when both FB₂ and FB_(OSD) are at a low level,FB₄₄ is at a low level. Said differently, FB₄₄ represents the fastblanking signal for the image from the Scart2 connector 38 (representedby R₂, G₂ and B₂) with superimposed image from the OSD circuit 26(represented by R_(OSD), G_(OSD) and B_(OSD)).

A second RGB switch 42 receives on the one hand the signals R₄₀, G₄₀,B₄₀ from the first RGB switch 40 and on the other hand the signals R₄₆,G₄₆, B₄₆ from the RGB generator 46. The second RGB switch 42 iscontrolled by the output of the first OR-gate, i.e. the fast blankingsignal FB₄₄. The second RGB switch 42 outputs a RGB signal on pins R₄₂,G₄₂ and B₄₂ which is selectively the signal from the first RGB switch 40or the signal from the RGB generator 46 depending on the fast blankingsignal FB₄₄.

More precisely, the second RGB switch 42 outputs the RGB signal receivedfrom the first RGB switch 40 when the fast blanking signal FB₄₄ is at ahigh level and the RGB signal received from the RGB generator 46 whenthe fast blanking signal FB₄₄ is at a low level. The video signalrepresented by R₄₂, G₄₂ and B₄₂ at the output of the second RGB switch42 is thus the image from the RGB generator 46 on which is superimposedthe image for the first RGB switch 40, i.e. the image from the Scart2connector 38 with superimposed OSD (from OSD circuit 26).

A second OR gate 48 receives the fast blanking signal FB₄₄ from thefirst OR gate 44 and the fast blanking signal FB₄₆ from the RGBgenerator 46. In a way similar to the first OR gate 44, the second ORgate 48 realises a logical OR operation between these two signals andgenerates on its output FB₄₈ a fast blanking signal corresponding to thevideo signal generated on the output of the second RGB switch 42. Thisfast blanking signal FB₄₈ is then passed via a 10 dB amplifier 49 to pin16 of the Scart connector 28 to be used as a fast-blanking signal in theapparatus, for instance display, connected to the Scart connector 28.

The amplifier 49 allows to output on pin 16 a sufficient voltage to beused by the apparatus connected to the Scart connector 28 (e.g. display)in spite of the possible voltage reductions in OR-gates 44 and 48 and ofpossible uneveness between the various initial blanking signals FB₂,FB_(OSD) and FB₄₆.

A luminance switch 34 receives a composite video signal CVBS from theCVBS generator 22 and a luminance signal Y from the S-Video generator24. The luminance switch 34 is controlled by a control signal M from themicro-processor 30 to selectively output to pin 19 of the Scartconnector 28 the composite video signal CVBS or the luminance signal Y.

A chrominance switch 36 receives a chrominance signal C from the S-Videogenerator 24 and the red signal R₄₂ from the second RGB switch 42. Thechrominance switch 36 is controlled by a command N to selectively outputto pin 15 of the Scart connector 28 the red signal R₄₂ or thechrominance signal C. Command N is generated at the output of a AND-gate50 which first input receives the control signal M and which secondinput receives the inverted fast-blanking signal of pin 16 (i.e. thefast-blanking signal FB passed through an inverter 52).

A first ground switch 35 allows to selectively connect pin 11 of theScart connector 28 to the green signal G₄₂ from the second RGB switch 42or to ground. Similarly, a second ground switch 37 allows to selectivelyconnect pin 7 of the Scart connector 28 to the blue signal B₄₂ from thesecond RGB switch 42 or to ground. Both the first ground switch 35 andthe second ground switch 37 are controlled by the signal N controllingthe chrominance switch 36.

The VCR can work according to two possible modes, namely a first modewhere the Scart connector 28 carries a CVBS signal and a second modewhere the Scart connector 28 is allowed to carry a S-Video signal(“S-Video via Scart mode”). The working mode can be selected throughmenus generated by the micro-processor 30 and the OSD circuit 26 andstored in a memory accessible by the micro-processor 30. The two workingmodes will be described now with further details.

In the first mode, the micro-processor 30 sets the control signal M tolow level (0) whereby the luminance switch 34 connects the output of theCVBS generator 22 to pin 19 of the Scart connector 28.

As the control signal M is low, the output (signal N) of the AND-gate 50is also low, whereby the chrominance switch 36 connects the red signaloutput R₄₂ of the second RGB switch 42 with pin 15 of the Scartconnector 28 and whereby the ground switches 35, 37 connect respectivelythe green signal output G₄₂ and the blue signal output B₄₂ of the secondRGB switch 42 with pins 11 and 7 of the Scart connector 28.

In the second mode, it is possible to use the Scart connector 28 forS-Video: this mode is thus called “S-Video via Scart” and can be chosenby the user through menus.

If no S-Video signal is available at the output of the S-Video generator24, for instance when the tape read by the VCR is a VHS tape, thecontrol signal M remains at low level (0) and the connections realisedby the switches are thus identical to those described in the first mode.

When the user has selected the “S-Video via Scart” mode and when theS-Video generator 24 is active, the micro-processor 30 sets the controlsignal M to 1 (high level).

Under these conditions, if nothing from the second RGB switch 42 is tobe superimposed on the S-Video signal, the fast blanking signal FB₄₈from the second OR-gate is low; the signal from inverter 52 will then behigh and hence the output of the AND-gate 50 will also be high:accordingly, the chrominance switch 36 will connect pin 15 to thechrominance output C of the S-Video generator and the ground switches35, 37 will connect pins 7 and 11 to ground (in order to avoidcross-talk). Of course, as the control signal M is high, the luminanceswitch 34 connects pin 19 to the luminance output Y of the S-Videogenerator 24.

Still under the same conditions (high control signal M), the second RGBswitch 42 can output a RGB signal to be superimposed (or inserted) onthe video signal from the S-Video generator 24. During the insertion,the fast blanking signal FB₄₈ is high; the output of the inverter 52 isconsequently low which sets the output of the AND-gate 50 to low level:the chrominance switch 36 and the ground switches 35, 37 then connectthe R, G, B outputs respectively to pins 15, 11 and 7. It is to be notedthat, in the present embodiment, the control of the luminance switch 34remains unchanged during insertion, so that pin 19 of the Scartconnector 28 remains connected to the luminance output Y of the S-Videogenerator 24.

According to a possible variation, the chrominance switch 36 iscontrolled by control signal M: only the connections in the groundswitches 35, 37 are changed when the fast-blanking signal FB is highduring the “S-Video via Scart” mode, the chrominance switch 34maintaining the connection between the chrominance output C and pin 15.

A second embodiment of the invention is illustrated on FIG. 2. The partswhich are similar to the first embodiment will not be described onceagain.

The luminance switch 34, the chrominance switch 36 and the groundswitches 35, 37 are controlled by a command M from the micro-processor30. (Countrarily to FIG. 1, the fast blanking signal is not used tocontrol any of said switches.)

A video generator 54 comprises a composite output CVBS, S-Video outputs(namely a luminance output Y and a chrominance output C) and RGB outputs(namely a monochrome red output R₅₄, a monochrome green output G₅₄, amonochrome blue output B₅₄ and a fast blanking signal output FB₅₄). Thevideo generator 54 carries on said outputs three representations(composite, S-Video and RGB) of the same video sequence.

The RGB outputs: R₅₄, G₅₄, B₅₄ of the video-generator 54 are connectedas inputs to the second RGB switch 42. The RGB outputs of the first RGBswitch 40 are also input to the second RGB switch, as described inrelation with the first embodiment.

The video generator 54 carries on its output FB₅₄ a fast-blanking signalsynchronised with the RGB signals R₅₄, G₅₄, B₅₄ and which is input tothe second OR-gate 48. The RGB signals can be muted by the videogenerator 54; the fast-blanking signal is then FB₅₄ at low level.

The micro-processor 30 is linked with the OSD circuit 26 by a bus l andto the video generator 54 by a bus J. The micro-processor 30 is alsoconnected to pin 8′ of the Scart2 connector 38 via a connection K. Pin8′ is generally called “Slow switch” and carries information whether avideo signal is incoming from the Scart2 connector 38 with a timeconstant largely longer than fast blanking signals.

As previously described, when a S-Video signal is available on outputsY, C of the video generator 54 and when the “S-Video via Scart” mode isselected by the user, the luminance switch 34 connects output Y to pin19 of the Scart connector 28, the chrominance switch 36 connects outputC to pin 15, the first ground switch 35 connects pin 11 to ground andthe second ground switch 37 connects pin 7 to ground. The RGB signalsR₅₄, G₅₄, B₅₄ from the video generator 54 are muted.

The video apparatus can then operate according to two alternativeprocesses when OSD insertion is required. The process to be used isselected according to a prior choice made by the user (for instancethrough “User Preferences” menus) and recorded in a memory accessible tothe microcomputer 30. It should be noted however that one only of thetwo processes could be implemented in a given video apparatus.

According to a first process, when a RGB video signal from the Scart2connector 38 is detected by the micro-processor 30 (thanks to connectionK as explained above) or when the micro-processor 30 has to sendinstructions for OSD insertion to the OSD circuit 26 on bus I, theluminance switch 34 connects back the CVBS output of the video generator54 to pin 19 of the Scart connector 28, the chrominance switch 36connects back the red output R of the second RGB switch 42 to pin 15,the first ground switch 35 connects back the green ouput G of the secondRGB switch 42 to pin 11 and the second ground switch connects back theblue output B of the second RGB switch 42 to pin 7. Of course, theswitches are controlled by the micro-processor 30 through control lineM. The RGB signals R₅₄, G₅₄, B₅₄ from the video generator 54 remainmuted.

According to the first process, the CVBS signal is thus used instead ofthe S-Video signal during OSD insertion (either from Scart2 or from theOSD circuit); this leads to a loss in image quality but to a very secureOSD insertion as the Scart switch is used in a totally conventionalmanner.

It is important to point out that this process can be used in a videoapparatus where the video generator 54 does not generate RGB signals, asfor instance some S-VHS VCRs.

According to the second process, when a RGB video signal from the Scart2connector 38 is detected by the micro-processor 30 (thanks to connectionK as explained above) or when the micro-processor 30 has to sendinstructions for OSD insertion to the OSD circuit 26 on bus I, themicro-processor 30 controls through line M the chrominance switch 36,the first ground switch 35 and the second ground switch 37 respectivelyto connect the red output R, the green ouput G and the blue output B ofthe second RGB switch 42 back to pins 15, 11 and 7 of the Scartconnector 28; simultaneously, the micro-processor 30 controls the videogenerator 54 to unmute the video signal on the RGB outputs, that is tosend out signals on outputs R₅₄, G₅₄, B₅₄ and FB₅₄.

The video sequence represented by R₅₄, G₅₄, B₅₄ is then mixed by thesecond RGB switch with the insertion to be realised (coming from thefirst RGB switch 40 and comprising the video sequence from Scart2 withsuperimposed video sequence from the OSD circuit 26). The mixing isrealised as described in relation to the RGB generator 46 of the secondembodiment. Due to the connection of the switches indicated above, thesecond RGB switch 42 sends out the desired video sequence (withinsertion) to pins 15, 11 and 7 of the Scart connector 28 in synchronismwith the fast-blanking signal FB₄₈ output from the second OR-gate 48.

For this second process, the connection realised by the luminance switch34 need not be taken into consideration as neither the luminance signalY nor the composite signal CVBS are used. However, in order to simplifythe circuitry, only one control line M is used and the luminance switch34 will connect the composite signal output CVBS to pin 19 of the Scartconnector 28.

To sum up, according to the second process, the video generator 54 isused as third source of RGB signal in addition to the OSD circuit 26(first source) and the Scart2 connector 38 (second source). The rulesfor priority of superimposition (first source on top, then secondsource, lastly third source) are determined by the connection of thefirst and second RGB switches 40, 42 as explained in the firstembodiment.

A preferred embodiment of the video generator 54 is represented at FIG.3.

In this embodiment, three possible sources of video signal are providedfor the video generator 54, namely a composite video signal from pin 19′of the Scart2 connector 38, a composite video signal generated by aconventional tuner and demodulator front-end 56 and a MPEG2 signalgenerated as a bit stream by a drum set 64 with magnetic heads readingon a tape recorded according to the D-VHS format.

A source switch 58 controlled by the micro-processor 30 depending oninstructions from the user allows to selectively connect pin 19′ or thefront-end 56 to the input of a digital generator 60, for instancerealised by a Philips SAA7114 video decoder followed by a NEC uPD61050MPEG2 encoder. A digital generator is a circuit generating digitalstreams based on analog signals, as for instance a MPEG2 encoderassociate with a video decoder.

A Philips SAA6700H bit-stream processor 62 can receive the MPEG2 streamgenerated by the digital generator 60 and convert it into a bit streamto be recorded on a magnetic tape by the drum set 64. The bit-streamprocessor 62 can also convert a bit stream read on a magnetic tape intoa MPEG2 stream which is then output to a first input of a digital switch66.

A second input of the digital switch 66 receives the MPEG2 streamgenerated by the digital generator 60 mentioned above. The digitalswitch 66 allows to selectively output the MPEG2 stream generated by thebit stream processor 62 or the MPEG2 stream generated by the digitalgenerator 60 to a digital decoder 68, for instance a SGS—Thomson STI5500MPEG2 decoder. This IC includes a video encoder realising the compositevideo signal CVBS, the S-Video signals Y, C and the RGB signals R₅₄,G₅₄, B₅₄ based on the MPEG2 stream output by the digital switch 66.

When a magnetic tape is read by the drum set 64, the micro-processor 30controls the digital switch 66 to connect the bit stream processor 62 tothe DIGITAL decoder 68. The bit stream read from the tape is thusconverted into a MPEG2 stream by the bit-stream processor 62 and thenoutput as video signals by the DIGITAL decoder 68 according to the 3possible formats CVBS, S-Video and RGB.

According to another possible way of operation called “DigitalImprovement”, the digital switch 66 can connect the output of thedigital generator 60 to the input of the digital decoder 68: thecomposite signal selected by the source switch 58 (i.e. the compositesignal from the tuner and demodulator 56, or the composite signal fromthe Scart2 connector 38) is converted to a MPEG2 stream by the digitalgenerator 60 and then to video signals according to CVBS, S-Video andRGB formats by the digital decoder 68.

This allows to generate S-Video- and RGB-format signals thanks toexisting circuits of the machine, thus without the need for specificcircuits for this purpose. Moreover, as the initial composite signal ispassed through the filters inherently included in the digital generator60 to realise notably the analog-to-digital conversion, the quality ofthe images is enhanced.

When the “Digital Improvement” is applied to the composite signal comingfrom the Scart2 connector 38, that is when the source switch connectspin 19′ with the DIGITAL generator 60 and when the digital switch 66connects the DIGITAL generator 60 with the DIGITAL decoder 68, theinitial synchronisation of the composite signal on pin 19′ with the RGBand fast blanking signals on pins 15′, 11′, 7′ and 16′ is lost by themomentary use of MPEG2. The micro-processor 30 then mutes the RGBsignals from the Scart2 connector 38 thanks to the muting circuit 45. Inthis case, the micro-processor 30 sends instructions to the OSD circuit26 to display a message indicating that the signals coming on pins 7′,11′ and 15′ are unavailable and that they can be made available byleaving the “Digital Improvement” mode: for instance, the message canread “OSD from Scart2 muted—To resume OSD, please exit DigitalImprovement”.

According to a possible variation applicable to any embodiment, groundswitches 35 and 37 can be omitted, the green output G₄₂ and blue outputB₄₂ of the second RGB switch 42 being directly connected to pins 11 and7 of the Scart connector 28. This solution could lead to cross-talkproblems but it is cheaper.

1. Video apparatus with a first connector for outputting first RGBsignals, with a second connector for receiving second RGB signals, andwith an On-Screen Display circuit generating third RGB signals, whereina RGB generator generates fourth RGB signals, a first RGB switch isconnected to the second connector and to the On-Screen Display circuitfor receiving respectively said second RGB signals and said third RGBsignals, the first RGB switch outputs fifth RGB signals, in that asecond RGB switch is connected to the first RGB switch and to the RGBgenerator for receiving respectively said fifth RGB signals and saidfourth RGB signals, the second RGB switch outputs the first RGB signals,the first RGB switch is controlled by a first fast-blanking signalgenerated by the On-Screen Display circuit, a first OR-gate generates asecond fast-blanking signal based on said first fast-blanking signal andon a fast-blinking signal of the second connector, and a second OR-gategenerates a third fast-blanking signal based on said secondfast-blinking signal and on a fast-blanking signal of the RGB generator.2. Video apparatus according to claim 1, wherein said thirdfast-blanking signal is output on a pin of the first connector.
 3. Videoapparatus according to claim 1, wherein said third fast-blanking signalis output on a pin of the first connector through an amplifier.
 4. Videoapparatus with a first connector for outputting first RGB signals, witha second connector for receiving second RGB signals, and with anOn-Screen Display circuit generating third RGB signals, wherein a RGBgenerator generates fourth RGB signals, a first RGB switch is connectedto the second connector and to the On-Screen Display circuit forreceiving respectively said second RGB and said third RGB signals, thefirst RGB switch outputs fifth RGB signals, a second RGB switch isconnected to the first RGB switch and to the RGB generator for receivingrespectively said fifth RGB signals and said fourth RGB signals, thesecond RGB switch outputs the first RGB signals, and a source switchallows to connect a composite video signal pin of the second connectorto a digital generator, wherein a digital switch allows to connect thedigital generator to a digital decoder generating said fourth RGBsignals and wherein a muting circuit is inserted between the secondconnector and the first RGB switch.
 5. Process for controlling a videoapparatus according to claim 4, comprising the steps of: controlling thesource switch to connect the composite video signal pin of the secondconnector to the digital generator; controlling the digital switch toconnect the digital generator to the digital decoder; controlling themuting circuit to mute said second RGB signals.
 6. Process according toclaim 5, further comprising the subsequent step of controlling theOn-Screen Display circuit to output RGB signals indicating said secondRGB signals are muted.